Besides betas I spend a lot of time tinkering on motorbikes (mainly Italian) and there is quite a thriving market in people supplying uprated battery earth and starter motor cables. These cables have markedly higher current capacity than the rather marginal OE ones and help to get big V-twins spinning over quickly and starting much more easily, as the full current potential is delivered straight away.

Would there be any benefit on doing something similar with a Beta, or are the OE cables correctly sized? Knowing Italian electrics of the 70s and 80s I'd be rather surprised if this were so...

I would have thought it was pretty easy to check by putting a meter across the cable and measure the volts drop when starting, especially if you disconnect the ignition so it does not start and hence you get a good few seconds of churning. You can also then do the 'is it getting warm' test, but the volts drop will let you know if there is an issue, it should be be pretty much 0 volts across the cable, all the volts should be across the starter in a perfect world.

I must say that looking at the cables I would be surprised if they were a big issue, I would look at connections before I worried about the cables tbh.

Thanks chaps. It wasn't really in connection with any observed problem, more a case of 'I wonder if it's the same as with the bikes'? Having said that, the cables are now at least 35 years old on my car, and one would assume that oxidation has reduced the cable's electrical capacity (or raised its resistance, to be more correct) to some degree. But there are probably many more pressing things to worry about than that, to be honest.

The last point about corrosion is valid and is about the connection between the cable and connector as well as what it connects to. Measuring the voltage drop across the cable and connectors should let you know of any issues